This paper describes the investigation of the interfacial chemistry that enables formation of a multi-electron ground-state charge transfer (CT) complex of oleate-coated PbS quantum dots (QDs) and tetracyanoquinodimethane (TCNQ) in CHCl3 dispersions. Thermodynamically spontaneous electron transfer occurs from sulfur ions on the surfaces of the QDs (radius = 1.6 nm) to adsorbed TCNQ molecules, and creates indefinitely stable ion pairs that are characterized by steady-state visible and mid-infrared absorption spectroscopy of TCNQ, and NMR spectroscopy of the protons of oleate ligands that coat the QDs.  The combination of these techniques shows that: (i) each QD reduces an average of 4.5 TCNQ molecules; (ii) every electron transfer event between the QD and TCNQ occurs at the QD surface; (iii) sulfur ions on the surfaces of the QDs (and not delocalized states within the QDs) are the electron donors; and (iv) some TCNQ molecules adsorb directly to the surface of the QDs, while others adsorb upon displacement of oleate ligands.

Spontaneous multi-electron transfer from the surfaces of PbS quantum dots to TCNQ

246th National Meeting (2013)

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